The full-sized photo is at the Library of Congress Online, and is part of their Civil War Photograph collection. It is a copy photo made by the Library of Congress in 1961 from a tintype*. The original tintype was owned/loaned by a Mr. G.K. Holmes, Cornwall Bridge, Conn.
CREATED/PUBLISHED between 1860 and 1865, re-photographed 1961.
MEDIUM 1 photographic print.
REPOSITORY Library of Congress Prints and Photographs Division Washington, D.C. 20540 USA
CALL NUMBER Civil War Reference File
REPRODUCTION NUMBER LC-B8184-10696 DLC (b&w film copy neg.)
COLLECTION Selected Civil War photographs, 1861-1865 (Library of Congress)
DIGITAL ID (b&w film copy neg.) cwp 4a40902
NOTES American Memory edition timeline. No. 1104
* The description above from the Library of Congress. We received an email in January 2012 with the following informtion:
... in regards to the image of the two seated Zouaves located in the banner at the top of your [blog] page. It is noted that the image is located at the National Archives and was reproduced from a tintype which would be incorrect. The original image is an ambrotype which is why you see the two cracks across the image where the glass has broken. A tintype can be reproduced from a ambrotype. An ambrotype cannot be reproduced from a tintype however. I currently own the original image...